This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
In recent years, mobile broadcast solutions have been standardized by different organizations, such as the 3rd Generation Partnership Project (3GPP) MBMS. 3GPP MBMS enables the resource-efficient delivery of popular multimedia content to the mobile users. A MBMS client can receive content via download delivery, streaming delivery and a combination of streaming delivery and download delivery.
MBMS is a feature described in 3GPP Release 6. However, MBMS may be deployed by operators in only a few areas where it is cost efficient to have broadcast/multicast distribution of popular content. When MBMS subscribers move to areas where there is no MBMS coverage, the operator may distribute the MBMS content in unicast mode. In such a use case, application/transport layer signaling is required in order to ensure the seamless handover between broadcast/multicast mode reception and unicast mode reception of MBMS content.
One of the objectives of a 3GPP SA4 Release 7 work item on MBMS user service extensions is to specify the application/transport layer signaling needed for MBMS content distribution in unicast mode (over streaming and interactive bearers). Another objective is to specify optimization techniques for MBMS content delivery.
Table 1 below shows the current working assumptions in 3GPP SA4 for the mapping between protocols to be used in broadcast/multicast and unicast modes.
TABLE 1Download onlyDeliveryStreaming onlyStreaming + DownloadMethodDelivery MethodDelivery MethodsMBMS ContentFLUTE/UDPMBMS StreamingMBMS StreamingDistribution usingFrameworkFrameworkBroadcast/MulticastRTP/UDP forRTP/UDP for mediaBearersmedia transporttransportRTP/UDP forRTP/UDP for FECFEC transporttransport +FLUTE/UDP for filedownloadMBMS ContentOMA-PUSHPSSePSSeDistribution usingfor FDTRTSP for sessionRTSP for sessionUnicast Bearerstransfercontrolcontrol(For roamingHTTP GETRTP/UDP forRTP for mediaMBMS clients)requests formedia transporttransportindividual filesFLUTE/UDP for filedownload in the sameRTSP session
The File Delivery over Unidirectional Transport (FLUTE) protocol is discussed in the Internet Engineering Task Force (IETF) Request for Comments (RFC) 3926, available at www.ietf.org/rfc/rfc3926.txt. The User Datagram Protocol (UDP) is discussed in IETF RFC 768, available at www.ietf.org/rfc/rfc0768.txt. The Real-time Transport Protocol (RTP), a transport protocol for real-time applications, is discussed in IETF RFC 3550, available at www.ietf.org/rfc/rfc3550.txt. The Real Time Streaming Protocol (RTSP) is discussed in IETF RFC 2326, available at www.ietf.org/rfc/rfc2326.txt.
The 3GPP Packet-switched Streaming Service (PSS) is the 3GPP's solution for enabling packet-switched streaming in mobile devices. PSS defines protocols and media codecs for enabling the streaming service for mobile devices. PSS is based on RTSP for session setup and control. 3GPP Packet-switched Streaming Service enhancements (PSSe) are currently being defined in 3GPP. The goal of these enhancements is to define extensions to 3GPP PSS Release No. 6 to optimize the streaming service. A general description of PSS can be found in 3GPP TS 26.233 V6.0.0 (2004-09): Transparent end-to-end packet switched streaming service (PSS); General description (Release 6), available at www.3gpp.org/ftp/Specs/archive/26_series/26.233/. The PSS transport protocols and codecs are specified in 3GPP TS 26.234 V7.2.0 (2007-03) and are available at www.3gpp.org/ftp/Specs/archive/26_series/26.234/.
Section 7.4 of 3GPP TS 26.346-730 describes the usage of the Open Mobile Alliance (OMA) Push mechanism for MBMS download, when MBMS bearers are not available, in two steps. With this mechanism, the MBMS user equipment (UE) first registers its Mobile Station Integrated Services Digital Network (MSISDN) with the Broadcast Multicast Switching Center (BM-SC) to receive the download sessions using OMA Push. The BM-SC then distributes a FLUTE file delivery table (FDT) instance, which allows the MBMS UE to fetch files of interest.